APPLE BREEDING FOR DISEASE RESISTANCE IN LATVIA

In the relatively cool climate of Latvia, with a 135-140 day active growth season (over 10°C) and winter temperatures below -30°C every 5-10 years, few monogenic scab resistant apple cultivars introduced from other countries have so far shown promise in cultivar trials.
On the other hand, a number of local cultivars and those grown commercially in the Baltic countries possess good polygenic resistance to scab and other diseases.
The aim of our breeding program was to obtain new apple cultivars well adapted to the Baltic climate and possessing multiple resistance to scab, mildew, different fruit rots and Phyllosticta leaf blotch.
Good tree habit, early and heavy yields, attractive fruit colour and shape, good fruit flavour and storage, tolerance to winter and spring frosts were other priorities in the program.
In 1989-1993 crosses of scab resistant cultivars and hybrids ‘Liberty’, BM 41497, Angers 814 (V_f) and SR 0523 (V_m) were made with apple cultivars ‘Atvasara’, ‘Antonovka’, ‘Iedzenu’, ‘Forele’, ‘Talvenauding’ and with 13 hybrids obtained from a previous breeding program, where ‘Iedzenu’ had been crossed with ‘Lawfam’, ‘Lobo’, ‘Melba’, ‘Kuban 15-42’, ‘Slava Peremozhtsam’ and ‘Starkrimson’. The obtained 6000 seedlings from 29 crossing combinations were first evaluated in the greenhouse, then in 1995-2002 the more healthy seedlings were further evaluated in field unsprayed with fungicides.
For scab infection in the greenhouse, inoculum collected from heavily infected trees in the orchard was used.
The first selection included 140 seedlings which were propagated and planted for further trial since 2002. At present, 27 hybrid seedlings show the most promise and seem to combine several kinds of disease resistance with appreciable fruit and tree properties.

XI Eucarpia Symposium on Fruit Breeding and Genetics

L. Ikase, R. Dumbravs

Malus xdomestica, apple scab, powdery mildew, monogenic resistance, polygenic resistance

https://doi.org/10.17660/ActaHortic.2004.663.127